Rpm regulating system for internal combustion engines operating on injected fuel

ABSTRACT

AN R.P.M. REGULATING SYSTEM THAT INCLUDES A HYDRAULIC MOTOR ADAPTED TO DISPLACE THE FUEL QUANTITY CONTROL MEMBER OF A FUEL INJECTION PUMP DELIVERING FUEL TO AN INTERNAL COMBUSTION ENGINE, A SOLENOID VALVE THAT CONTROLS THE ADMISSION OF HYDRAULIC FLUID TO, AND ITS DRAINAGE FROM, SAID MOTOR AND AN ELECTRONIC CONTROL STAGE THE ENERGIZING OUTPUT SIGNAL OF WHICH, APPLIED TO SAID SOLENOID VALVE, IS GENERATED BY THE COMPARISON OF AN R.P.M. DEPENDENT ELECTRIC SIGNAL AND A SIGNAL RESPONSIVE TO THE POSITION OF SAID FUEL QUANTITY CONTROL MEMBER WITH A SIGNAL RESPONSIVE TO THE ARBITRARILY SET VALUE OF A DESIRED ENGINE OUTPUT.

United States Patent [72] inventors Eberhard Hofmann Kirchberg(Murr); Rolf Muller, Stuttgart-Zufienhausen; Heinrich Standt, Markgroningen- Talhausen, Germany [21] Appl. No. 844,053

[22] Filed July 23, 1969 [45] Patented June 28, I971 [73] Assignee Robert Bosch Grnbll Stuttgart, Germany [32] Priority July 25, 1968 Germany [54] RPM REGULATING SYSTEM FOR INTERNAL COMBUSTION ENGINES OPERATING 0N INJECTED FUEL 7 Claims, 4 Drawing Figs.

52 us. (:1 123/102 123/139AQ, 123/14o1v1c, l23/l98D s lnt.Cl F02d5/02 50 Field of Search 123/102, 139,139.11-,139.11 FP ,140,140.1,140.3,32 (E),

[56] References Cited UNITED STATES PATENTS 2,910,969 11/1959 Reggio l23/l40.1 3,407,793 10/1968 Lang 123/102 Primary Examiner-Laurence M. Goodridge Attorney Edwin E. Greigg ABSTRACT: An r.p.m. regulating system that includes a hydraulic motor adapted to displace the fuel quantity control member of a fuel injection pump delivering fuel to an internal combustion engine, a solenoid valve that controls the admission of hydraulic fluid to, and its drainage from, said motor and an electronic control stage the energizing output signal of which, applied to said solenoid valve, is generated by the comparison of an r.p.m.dependent electric signal and a signal responsive to the position of said fuel quantity control member with a signal responsive to the arbitrarily set value of a desired engine output.

PATENIEU JUN28 1911 3 D 5 m 54 O sum 2 or 3 INVENTORS Eberhard HOFMANN Rolf MULLER Heinrich STAUDT their ATTORNEY PATENIED JUN28 I97! SHEET 3 BF 3 INVENTORS Eberhard HQFMANN Rolf MULLER HeinrichSTAUDT RPM REGULATING SYSTEM FOR INTERNAL COMBUSTION ENGINES OPERATING ON INJECTED FUEL BACKGROUND, OBJECT AND SUMMARY OF THE INVENTION This invention relates to an r.p.m. regulating system for internal combustion engines, particularly diesel engines, operating on injected fuel. The regulating system is of the type that includes a hydraulically operated motor adapted to displace a fuel control member for varying the fuel quantities to be injected into the combustion chambers of the engine by a fuel injection pump.

It is an object of the invention to provide an improved system of the aforenoted type, wherein the fuel quantities to be injected are determined as a function of electrically sensed variables, such as the rpm. of the engine or other operational parameters.

Briefly stated, according to the invention, a solenoid valve controls the admission of hydraulic fluid to, and its discharge from, a hydraulic setting motor which, accordingly, shifts a fuel quantity control member of a fuel injection pump. The solenoid valve is energized by electric signals which result from a comparison of a signal depending on a variable associated with the operation of the engine (for example, the engine r.p.m.) and a signal depending on the actual momentary position of said fuel quantity control member with a signal de pending on a desired preset output of said engine.

The invention will be better understood and further objects, as well as advantages, will become more apparent from the following detailed specification of a preferred, although exemplary, embodiment of the invention taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional side elevational view of one part of a preferred embodiment including a hydraulic setting motor;

FIG. 2 is a sectional side elevational view of the same part taken along another sectional plane;

FIG. 3 is a front elevational sectional view of another part of the preferred embodiment including the upper portion of the hydraulic setting motor; and

FIG. 4 is a diagrammatic view including the preferred embodiment in its entirety.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIGS. 1 and 4, there is shown in broken lines a fuel injection pump to the outside of which there is attached a hydraulic setting motor generally indicated at 11. At its upper portion the motor 11 includes a pressure chamber 12 in which there is disposed a membrane 13 which is displaceable by a hydraulic fluid, the admission of which to, and discharge from, the pressure chamber 12 is controlled by a solenoid valve 23 (FIGS. 2 and 4). The motion of membrane 13 is transmitted through a stem 14, a collar 15 and a bell crank 16 to a fuel quantity control rod 17 of the fuel injection pump MB. In order to equalize the play of the control rod 17, there is provided a coil spring 31 which is compressed between a wall of the setting motor housing and the control rod 17 (FIG. 2).

Between a spring seat disc 14a secured to the stem 14 and an insulating block Mb surrounding stem 141 and mounted on a fixed housing part 14c, there is disposed a coil spring 18 exerting on stem 14 a force which is opposed to that of the hydraulic pressure in chamber 12. If the solenoid valve 23, upon energization by an appropriate signal, establishes communication between chamber 12 and a hydraulic fluid under pressure, for example, fuel driven by a fuel pump 36 and taken from a fuel line 29 (FIG. 4), the stem 14 will be displaced downwardly against the force of coil spring 18. Conversely, if the solenoid valve 23, upon energization by an appropriate signal, establishes communication between chamber 12 and a return conduit 29a, the fuel in chamber 12 will be drained through conduit 29a and returned to tank 2% by virtue of coil spring 18 which now displaces the stem 14 upwardly and moves membrane 13 into chamber 12. Depending upon the direction of movement of stem 14, the fuel quantity control rod 17 will be displaced thereby in the direction of fuel increase or fuel decrease.

Referring now to FIGS. 2 and 3, the fuel quantity control rod 17 may be brought into a zero (fuel cutoff) position regardless of its momentary position or the position of membrane 13, by operating an outer cutoff lever 33 which, in turn, actuates an arm 32 pivotally secured to the housing of motor 11 and engaging, in its position of rest, a wall of the fuel injection pump it). When actuated, arm 32 pulls the fuel quantity control rod into its zero fuel position.

The devices affecting the energization of solenoid valve 23 will now be described.

In the housing of hydraulic setting motor 11 there is disposed an inductive r.p.m. indicator 21 of known structure which is driven by the cam shaft 22 of the fuel injection pump 10 and which generates an rpm-dependent electric output signal.

The insulating block 14b carries an electric coil 19 surrounding stem 14. To the latter there is coaxially affixed a cylindrical ferrite core 20 which moves with stem 14 as a unit and which is adapted to affect the inductivity and thus the signal output of coil 19. It is thus seen that by virtue of the mechanical connection between the core 20 and the fuel quantity control rod 17, the momentary position of the latter will determine the magnitude of the signal output of coil 19.

The ferrite core 20 may be set by an adjusting device 20' -preferably self-locking nut relative to coil 19 and against the force of a spring 20" for determining the basic signal output of coil 19.

With the control means for the arbitrary setting of the engine output or performance such as the accelerator pedal in automotive vehicles there is connected a performance indicator 35 which generates an output signal as a function of the desired engine perfonnance.

The aforedescribed three output signals that is, the output of r.p.m. indicator 21, that of coil 19 and that of performance indicator 35 -are applied as input signals to an electronic control stage 34 which, by means of known electronic components, compares these input signals and as a result generates an output signal which, by means of conductor 38, is applied to a solenoid valve 23. This process will become more apparent when the operation of the embodiment will be described.

It is to be noted that the aforedescribed adjustability of the ferrite core 20 relative to coil 19 by means of adjusting nut 20 facilitates the basic setting of the entire regulating system, since tolerances of manufacturing do not have to be compensated for in the electric components of the electronic control stage 34.

In order to obtain simple electric connections with the electric components associated with the setting motor 11, to the inside of the closure plate 24 of the setting motor 11 there is secured a conductor plate 25, the conductor strips or terminals of which are in contact with cantilevered resilient metal fingers 26 which, through their other ends, are electrically coupled with the last-named electrical components. In the case of coil I9, the resilient contact finger 26 is affixed, by one end, to the insulating block 1417 and engages, with its free end, the conductor plate 25 (FIG. 1). Another example of design is shown in FIG. 2, where one end of the contact finger 26 associated with the solenoid valve 23, is secured to the conductor plate 25, while its free end resiliently engages an electric terminal of the solenoid valve 23.

The conductor plate 25 may be connected by a multipole plug 25a, preferably embedded in a synthetic resin, to the electronic control stage 34.

It is to be noted that by means of the axial vertical arrangement of the pressure chamber 12 on the one hand and the disposition of the inductive, actual position indicator 19, 20

coaxially inside return spring 18 on the other hand, a particularly significant saving in volume is obtained.

OPERATION OF THE PREFERRED EMBODIMENT Turning once again to FIG. 4, it is assumed that for a running engine the accelerator is set to a certain desired (e.g. full load range) value of engine performance. Accordingly, the performance indicator 35 coupled with the accelerator generates a corresponding electric signal which is applied to the electronic control 34. As a response, the latter transmits through conductor 38 an energizing signal which is applied to the solenoid valve 23.

Part of the fuelunder pressure, driven by pump 36 and passing through filter 37, is admitted from fuel line 29 to solenoid valve 23. The other part of the pressurized fuel is admitted to the suction chamber (not shown) of the fuel injection pump 10 through the check valve 30 and a sinter body 28 of filter 27.

In response to the energizing signal, the solenoid valve 23 permits admission of the pressurized fuel to pressure chamber 12 and, as a result, the stem 14 will be displaced downwardly, setting the fuel quantity control rod 17 into a determined position. At the same time, the ferrite core 20 is shifted and thus the output signal of the coil 19 has changed, indicating to the electronic control 34 the actual value of the position of the control rod 17 (actual fuel delivery from the fuel injection pump to the internal combustion engine). A comparison by the electronic control stage 34 of the output signals taken from r.p.m. indicator 21, and the position indicator 19, 20 with the signal of the desired performance indicator 35 will adjust the energizing signal applied to solenoid valve 23 to a value where the fuel quantity control rod 17 is set to the determined position corresponding to the desired engine perforrnance.

It is now assumed that the load decreases. As a result, the engine r.p.m. increases. This increase generates in the inductive r.p.m. indicator 21 a proportionately changed electric signal which is applied to the electronic control stage 34 and is compared thereby with the desired value applied by indicator 35 and is transformed into a new, changed signal for the solenoid valve 23. This last'named signal energizes the solenoid valve 23 in a direction that permits drainage of fuel from the pressure chamber 12 of the setting motor 11 through return conduits 29a Proportionally to the volume of the fuel drained from the pressure chamber 12, the stem 14 is moved by the coil spring 18 upwardly and displaces through the collar l and the bellcrank 16 the fuel quantity control rod 17 of the fuel injection pump it) in the direction of decreasing fuel quantities. Thus, the injected fuel quantities are decreased and the rpm. again drops.

Simultaneously with the upward motion of the stem 14, the ferrite core 20 is displaced relative to the coil l9 resulting in a change in the inductivity of the coil 19 causing a change in the output signal thereof. This changed signal is, together with the signal of the r.p.m. indicator 21, compared with the desired value by the electronic control stage 34 and as soon as r.p.m. and load (injected fuel quantities) have assumed the values assigned to the operational condition under consideration, the regulating motion of the stem M of the regulating system is terminated. Should an excessive regulation occur, then an opposed signal is emitted by the electronic control 34 and as a result, the solenoid valve 23 establishes communication between the fuel pressure conduit 29 and the pressure chamber 12 so that the pressure admitted to the pressure chamber 12 causes the stem 14 to shift downward. Thereby the fuel quantity control rod 17 is again shifted in the direction of full load," that is, toward an increased fuel quantity.

In summary, it is thus seen that a signal characterizing the momentary position of the control rod 17 is transmitted to the electronic control 34 which compares the last-named signal and the signal transmitted by the rpm. indicator 21 with the desired values of the regulator characteristics given by the preset performance indicator 35 and causes a desired actuation of the solenoid valve 23.

If the engine operates uniformly in a stable range, that is, without load or r.p.m. fluctuations, the solenoid valve 23 switches in such a rapid, continuous sequence between pressure and drainage that the control rod 17 is practically stationary or vibrates only very weakly. Such weak vibration has no effect on the operation of the engine.

We claim:

l. in a system for regulating the r.p.m. of an internal combustion engine operating on fuel delivered thereto by a fuel injection pump, said system being associated with and causing displacement of the fuel quantity control member of said fuel injection pump as a function of a plurality of variables, the improvement comprising:

A. a hydraulic setting motor having:

1. a pressure chamber,

2. a solenoid valve controlling admission of hydraulic fluid to, and its discharge from, said pressure chamber,

3. means disposed in said pressure chamber and adapted to be displaced to an extent and in a direction dependent upon the pressure conditions in said pressure chamber,

4. mechanical means displaceable in response to said pressure conditions for moving said fuel quantity control member, said mechanical means including:

a. an axially reciprocable stem affixed to and movable as a unit with said means displaceable in said pressure chamber,

b. a collar mounted on and movable with said stem,

0. a pivotally movable bellcrank formed of one arm engaging said collar and another arm engaging said fuel quantity control member,

B. means generating an electrical signal responsive to a vari able changing as a function of the performance of said engine,

C. means generating an electrical signal responsive to the actual momentary position of said fuel quantity control member,

D. means generating an electrical signal corresponding to an arbitrarily set value of desired engine performance.

E. means comparing said signals defined in B and C with said signal defined in D and generating an electric energizing signal resulting from such comparison, and

F. means for applying said electrical energizing signal defined in E to said solenoid valve to effect operation thereof as defined in A 2. v

2. An improvement as defined inclaim 1, wherein said variable changing as a function of the performance of said engine is the r.p.m. thereof.

3. An improvement as defined in claim 1, wherein said means generating an electrical signal responsive to the actual momentary position of said fuel quantity control member includes:

A. an electric coil, and

B. a core movable in unison with said fuel quantity control member and relative to said coil to vary the inductivity thereof.

4. An improvement as defined in claim 3, wherein said core is affixed to said stem and movable therewith as a unit, said coil surrounds said stem and said core and is stationary with respect to said system.

5. In a system for regulating the rpm. of an internal combustion engine operating on fuel delivered thereto by a fuel injection pump, said system being associated with and causing displacement of the fuel quantity control member of said fuel injection pump as a function of a plurality of variables, the improvement comprising:

A. means generating an electrical signal responsive to a variable changing as a function of the performance of said engine,

B. means generating an electrical signal responsive to the actual momentary position of said fuel quantity control member, said last-named means including:

I. an electric coil,

2. a core movable in unison with said fuel quantity control member and relative to said coil to vary the inductivity thereof:

C. a hydraulic setting motor having:

l. a pressure chamber,

2. a solenoid valve controlling admission of hydraulic fluid to, and its discharge from, said pressure chamber,

3. means disposed in said pressure chamber and adapted to be displaced to an extent and in a direction dependent upon the pressure conditions in said pressure chamber,

4. mechanical means connected with said means disposed in said pressure chamber and with said fuel quantity control member, said mechanical means displaceable in response to said pressure conditions for moving said fuel quantity control member, said mechanical means including:

a. an axially reciprocable stem moving in unison with said means disposed in said pressure chamber, said core being affixed to said stem and movable therewith as a unit, said coil surrounding said stem and said core and being stationary with respect to said system,

b. adjusting means for arbitrarily changing the position of said core on and with respect to said stem,

D. means generating an electrical signal corresponding to an arbitrarily set value of desired engine performance,

E. means comparing said signals defined in A and B with said signal defined in D and generating an electric energizing signal resulting from such comparison, and

F. means for applying said electrical energizing signal defined in E to said solenoid valve to effect operation thereof as defined in C 2.

6. An improvement as defined in claim 5, wherein the adjusting means defined in C 4 b includes a self-locking nut threaded on said stem and a spring urging said core against said self-locking nut.

7. In a system for regulating the rpm. of an internal combustion engine operating on fuel delivered thereto by a fuel injection pump, said system being associated with and causing displacement of the fuel quantity control member of said fuel injection pump as a function of a plurality of variables, the improvement comprising:

A. a hydraulic setting motor having l. a pressure chamber,

2. a solenoid valve controlling admission of hydraulic fluid to, and its discharge from, said pressure chamber,

3. means disposed in said pressure chamber and adapted to be displaced to an extent and in a direction dependent upon the pressure conditions in said pressure chamber,

4. mechanical means connected with said means disposed in said pressure chamber and with said fuel quantity control member, said mechanical means adapted to be displaced in response to said pressure conditions and move said fuel quantity control member,

B. means generating an electrical signal responsive to a variable changing as a function of the performance of said engine,

C. means generating an electrical signal responsive to the actual momentary position of said fuel quantity control member,

D. means generating an electrical signal corresponding to an arbitrarily set valve of desired engine performance,

E. means comparing said signals defined in B and C with said signal defined in D and generating an electric energizing signal resulting from such comparison,

F. means for applying said electrical energizing signal defined in E to said solenoid valve to effect operation thereof as defined in A 2 G. a housing containing said hydraulic setting motor, said means generating an electric signal responsive to a varia b le changing as a function of the performance of said englne and said means generating an electric signal responsive to the actual momentary position of said fuel quantity control member,

H. a closure plate adapted to be removably secured to said housing,

I. exposed conductor means affixed to the inner face of said closure plate,

J. electric outlet means affixed to.the outer face of said closure plate and coupled to said exposed conductor means, and

K. resilient contact fingers establishing an electric connection between electric components within said housing on the one hand, and said exposed conductor means on the other hand, when said closure plate is secured to said housing. 

